This application is based on Japanese Patent Application No. 2001-283608 filed on Sep. 18, 2001, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to a refrigerant cycle system with an improved refrigerant-sealing performance. More particularly, the present invention relates to a discharge structure of gas refrigerant in a receiver of the refrigerant cycle system, which separates refrigerant from a refrigerant condenser into gas refrigerant and liquid refrigerant, and stores the liquid refrigerant therein. The present invention is suitably applied to a vehicle air conditioner.
2. Description of Related Art
In a conventional refrigerant cycle for a vehicle air conditioner, when heat from an engine compartment is transmitted to a receiver, liquid refrigerant stored within the receiver is boiled, and gas pressure within the receiver is increased. Therefore, a liquid refrigerant surface in the receiver becomes lower, and liquid refrigerant is discharged from the receiver to a downstream side. Accordingly, the liquid refrigerant stays in a condenser, high-pressure side refrigerant pressure is increased in the refrigerant cycle, and power consumed in a compressor is increased.
To overcome this problem, U.S. Pat. No. 6,374,632 proposes a refrigerant cycle system in which liquid refrigerant from a condenser flows into a receiver from upper and lower sides in the receiver. That is, in this refrigerant cycle system, an upper space of the receiver is cooled by latent heat of liquid refrigerant flowing from the upper side. However, a desiccant for adsorbing water contained in refrigerant is generally disposed within the receiver, and the refrigerant flow from the upper side in the receiver is restricted by the desiccant. As a result, the upper space of the receiver may not be sufficiently cooled using the liquid refrigerant introduced from the upper side.
In view of the foregoing problems, it is an object of the present invention to improve refrigerant sealing performance in a refrigerant cycle system.
It is an another object of the present invention to provide a refrigerant cycle system with a receiver, which prevents an increase of a gas pressure in the receiver even when the heat is transmitted into the receiver from an outside.
According to the present invention, a refrigerant cycle system includes a first refrigerant passage through which refrigerant after passing through a condensation portion of a condenser flows into a receiver, a second refrigerant passage through which liquid refrigerant stored at a lower side in the receiver flows outside the receiver, and a third refrigerant passage having two end portions with a predetermined pressure difference, through which gas refrigerant staying at an upper side in the receiver is discharged to a downstream side of the receiver. Accordingly, even when heat is transmitted into the receiver from an outside and liquid refrigerant in the receiver is boiled, because gas refrigerant at the upper side in the receiver is discharged outside the receiver through the third refrigerant passage, it can restrict the gas pressure in the receiver from being increased. As a result, it can prevent a liquid refrigerant surface in the receiver from being lowered due to an increase of the gas pressure in the receiver. That is, it can prevent refrigerant from over-flowing from the receiver toward the condenser. Therefore, refrigerant-sealing performance in the refrigerant cycle system can be improved, and COP of the refrigerant cycle system can be improved.
Preferably, the condenser includes a core portion at least including the condensation portion, and a header tank extending in the up-down direction to communicate with tubes of the core portion. Further, the receiver is integrated with the header tank, and each of the first and second refrigerant passages is a communication hole penetrating through the header tank and the receiver. Accordingly, the present invention can be effectively used for a refrigerant cycle system having a receiver-integrated condenser. In this case, the first refrigerant passage and the second refrigerant passage can be readily provided.
Preferably, the third refrigerant passage can be defined by a gas bypass pipe connected to the receiver from an outside of the receiver. Alternatively, a connection plate member can be inserted between the header tank and the receiver, and the third refrigerant passage is provided in the connection plate member. Alternatively, the third refrigerant passage can be provided in an approximately cylindrical body portion of the receiver while the body portion is integrally formed by punching or drawing. Accordingly, third refrigerant passage can be readily formed, and the gas refrigerant at the upper side in the receiver can be readily discharged.
Preferably, the second refrigerant passage is provided to generate a pressure loss therein, the third refrigerant passage has an outlet from which the gas refrigerant introduced in the third refrigerant passage from the upper side in the receiver is discharged, and the outlet of the third refrigerant passage is provided in the second refrigerant passage or at a downstream side of the second refrigerant passage. In this case, the third refrigerant passage readily has the predetermined pressure difference at the two end portions, and the gas refrigerant in the receiver can be effectively discharged.